/*
 * Copyright (c) 1996, 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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 */

package java.io;

import java.nio.charset.Charset;
import java.nio.charset.CharsetEncoder;
import sun.nio.cs.StreamEncoder;


/**
 * An OutputStreamWriter is a bridge from character streams to byte streams:
 * Characters written to it are encoded into bytes using a specified {@link
 * java.nio.charset.Charset charset}.  The charset that it uses
 * may be specified by name or may be given explicitly, or the platform's
 * default charset may be accepted.
 *
 * <p> Each invocation of a write() method causes the encoding converter to be
 * invoked on the given character(s).  The resulting bytes are accumulated in a
 * buffer before being written to the underlying output stream.  The size of
 * this buffer may be specified, but by default it is large enough for most
 * purposes.  Note that the characters passed to the write() methods are not
 * buffered.
 *
 * <p> For top efficiency, consider wrapping an OutputStreamWriter within a
 * BufferedWriter so as to avoid frequent converter invocations.  For example:
 *
 * <pre>
 * Writer out
 *   = new BufferedWriter(new OutputStreamWriter(System.out));
 * </pre>
 *
 * <p> A <i>surrogate pair</i> is a character represented by a sequence of two
 * <tt>char</tt> values: A <i>high</i> surrogate in the range '&#92;uD800' to
 * '&#92;uDBFF' followed by a <i>low</i> surrogate in the range '&#92;uDC00' to
 * '&#92;uDFFF'.
 *
 * <p> A <i>malformed surrogate element</i> is a high surrogate that is not
 * followed by a low surrogate or a low surrogate that is not preceded by a
 * high surrogate.
 *
 * <p> This class always replaces malformed surrogate elements and unmappable
 * character sequences with the charset's default <i>substitution sequence</i>.
 * The {@linkplain java.nio.charset.CharsetEncoder} class should be used when more
 * control over the encoding process is required.
 *
 * @author Mark Reinhold
 * @see BufferedWriter
 * @see OutputStream
 * @see java.nio.charset.Charset
 * @since JDK1.1
 */

public class OutputStreamWriter extends Writer {

  private final StreamEncoder se;

  /**
   * Creates an OutputStreamWriter that uses the named charset.
   *
   * @param out An OutputStream
   * @param charsetName The name of a supported {@link java.nio.charset.Charset charset}
   * @throws UnsupportedEncodingException If the named encoding is not supported
   */
  public OutputStreamWriter(OutputStream out, String charsetName)
      throws UnsupportedEncodingException {
    super(out);
    if (charsetName == null) {
      throw new NullPointerException("charsetName");
    }
    se = StreamEncoder.forOutputStreamWriter(out, this, charsetName);
  }

  /**
   * Creates an OutputStreamWriter that uses the default character encoding.
   *
   * @param out An OutputStream
   */
  public OutputStreamWriter(OutputStream out) {
    super(out);
    try {
      se = StreamEncoder.forOutputStreamWriter(out, this, (String) null);
    } catch (UnsupportedEncodingException e) {
      throw new Error(e);
    }
  }

  /**
   * Creates an OutputStreamWriter that uses the given charset.
   *
   * @param out An OutputStream
   * @param cs A charset
   * @spec JSR-51
   * @since 1.4
   */
  public OutputStreamWriter(OutputStream out, Charset cs) {
    super(out);
    if (cs == null) {
      throw new NullPointerException("charset");
    }
    se = StreamEncoder.forOutputStreamWriter(out, this, cs);
  }

  /**
   * Creates an OutputStreamWriter that uses the given charset encoder.
   *
   * @param out An OutputStream
   * @param enc A charset encoder
   * @spec JSR-51
   * @since 1.4
   */
  public OutputStreamWriter(OutputStream out, CharsetEncoder enc) {
    super(out);
    if (enc == null) {
      throw new NullPointerException("charset encoder");
    }
    se = StreamEncoder.forOutputStreamWriter(out, this, enc);
  }

  /**
   * Returns the name of the character encoding being used by this stream.
   *
   * <p> If the encoding has an historical name then that name is returned;
   * otherwise the encoding's canonical name is returned.
   *
   * <p> If this instance was created with the {@link
   * #OutputStreamWriter(OutputStream, String)} constructor then the returned
   * name, being unique for the encoding, may differ from the name passed to
   * the constructor.  This method may return <tt>null</tt> if the stream has
   * been closed. </p>
   *
   * @return The historical name of this encoding, or possibly <code>null</code> if the stream has
   * been closed
   * @revised 1.4
   * @spec JSR-51
   * @see java.nio.charset.Charset
   */
  public String getEncoding() {
    return se.getEncoding();
  }

  /**
   * Flushes the output buffer to the underlying byte stream, without flushing
   * the byte stream itself.  This method is non-private only so that it may
   * be invoked by PrintStream.
   */
  void flushBuffer() throws IOException {
    se.flushBuffer();
  }

  /**
   * Writes a single character.
   *
   * @throws IOException If an I/O error occurs
   */
  public void write(int c) throws IOException {
    se.write(c);
  }

  /**
   * Writes a portion of an array of characters.
   *
   * @param cbuf Buffer of characters
   * @param off Offset from which to start writing characters
   * @param len Number of characters to write
   * @throws IOException If an I/O error occurs
   */
  public void write(char cbuf[], int off, int len) throws IOException {
    se.write(cbuf, off, len);
  }

  /**
   * Writes a portion of a string.
   *
   * @param str A String
   * @param off Offset from which to start writing characters
   * @param len Number of characters to write
   * @throws IOException If an I/O error occurs
   */
  public void write(String str, int off, int len) throws IOException {
    se.write(str, off, len);
  }

  /**
   * Flushes the stream.
   *
   * @throws IOException If an I/O error occurs
   */
  public void flush() throws IOException {
    se.flush();
  }

  public void close() throws IOException {
    se.close();
  }
}
